The invention relates to an apparatus for adjusting the accommodation volume of a substantially tubular workpiece carrier having side walls and supported in a line.
Widely diverse conveyor means are known for the transporting of workpieces, and in this situation the emphasis is on those conveyors where the workpiece is picked up and conveyed in a carrier supported on the conveyor line. For example and preferably, thoughts turn to liquids packagings which are indeed directly transported on conveyor belts, even without a carrier but where disposition in a workpiece carrier is preferred during their handling, particularly filling and sealing, even just for positioning purposes.
Various sizes of packages are known. For example, spirits, wine and juices are transported in relatively small packages while in some cases juice, milk, oils and water are transported in larger packages. The rough classification indicated here is intended solely to illustrate the fact that packages to hold liquids--and of course other types of contents--are filled and used with different volumes. For the manufacturer and user of an apparatus of the type mentioned at the outset, it is desirable to produce workpieces, e.g., liquids packages from paper, for different contents on the same production machine after minor adjustment operations. If a part of the production machine is a conveyor with a line on which workpiece carriers are fixed, then the workpiece carrier should be convertible from a large volume workpiece to one which has a lesser volume.
For such an adjustability of the accommodation volume of workpiece carriers, in the case of conveyor means it is already known to incorporate lifting rails along the conveyance path, so that while having the same cross-section, the workpiece carrier has maximum depth and thus maximum accommodation volume without the lifting rails. When a lifting rail is installed it can for example be adjusted to suit a shorter package, because then the bottom of this shorter package is brought by the lifting rail in the tool carrier to such a height that the top edges of the workpiece carrier and the workpiece are the same for all volumes. Such a lifting rail is indeed adjustable but cannot be used on curved portions of a conveyor, which is a drawback. Furthermore, practice has shown that three different lifting rails have to be used for three different volumes for example.
Practical experience has shown furthermore that at some processing stations in the production machine a workpiece carrier, in respect of the delivery level, has to be raised, lowered and restored to the original position. When lifting rails are used, such raising or lowering out of the datum level can only be achieved at considerable cost.